The subject invention is directed to the lighting arts and, more particularly, to a luminous element of the type including a housing for mounting the luminous element in an installation opening and having at least one light-producing element with terminal contacts selectively engageable with contact elements provided in the housing. Luminous elements of the type under consideration herein are particularly well-suited for use in illuminating functional signals and for directly displaying functions in motor vehicles and will be described with particular reference thereto. However, it is to be understood that the present invention has other uses and can find utility in a wide range of applications.
Most prior art luminous elements used in automotive applications are designed in such a fashion that they are arranged directly onto a printed circuit board at one or more appropriate predetermined locations. The locations are selected so that following installation of the printed circuit board behind the transparent functional symbols to be illuminated by the transmitted light, such as behind an instrument panel of a motor vehicle, the luminous element is disposed adjacent the functional symbol.
In many instances, miniature incandescent lamps are used as the light-producing elements and are held in suitable housings or sockets. In that case, a recess is typically provided in the printed circuit board at a position where the luminous element is desired to be located. Incandescent lamp sockets can then be selectively inserted and detached from the recess on the printed circuit board. One benefit of this type of arrangement is an ease of exchangeability with respect to the luminous element.
Another previously known luminous element manufactured by Osram consists of a miniature incandescent bulb having terminal contacts which are respectively inseparably connected to a punched-out piece requiring a subsequent bending process. A subassembly is created by the miniature incandescent bulb and the two punched-out pieces. The subassembly is inserted from above into an appropriately designed plastic socket. The upper region of the socket defines a substantially cylindrical neck followed by a contact shoulder formed to adapt the socket housing member into an opening in a printed circuit board. A pair of substantially radially outwardly extending arms are formed by each of the two contact elements in the region above the contact shoulder i.e. in the region of the housing neck. The radially outwardly extending arms respectively act upon the upper or under side of the printed circuit board.
In the above system, a substantially circular recess is formed in the printed circuit board and includes two bulges corresponding to the arms of each contact element. The arms are insertable into the bulges. After twisting of the luminous element around its longitudinal axis by a predetermined angle, the radially outwardly extending arms of each contact element act upon a marginal zone of the opening in the printed circuit board to thereby fasten the luminous element to the printed circuit board. Simultaneously, at least one of the two contact arms of each contact element engages and serves to electrically contact a conductive track formed on the upper or under side of the printed circuit board to thereby supply electrical energy to the luminous element.
Although the previously known luminous elements described above are fairly easily exchangeable from their associated mountings, the manufacture of the luminous elements, however, is usually relatively complicated. One reason is that the sub-system including a miniature incandescent bulb and the electrical contact elements must usually first be pre-manufactured. The sub-system is then subsequently installed in proper aligned configuration into holding recesses formed in a housing socket. Since the contact elements of miniature incandescent bulbs typically as a rule consist of relatively thin flexible wires, insertion of such unstable sub-system into a housing socket typically requires a relatively large amount of effort.
Standard light-emitting diodes (LEDs) have been used in luminous elements. Typically, the LEDs have been handled in a customary fashion in the same manner as any other electronic component, namely by inserting the electrical connection contacts of the LEDs into corresponding bores formed in a printed circuit board and then firmly electrically and mechanically joining the electrical contact connections to the printed circuit board by means of soldering. Although this approach makes for a simple installation, it does not provide simple exchangeability of the light-generating element. While it is true that LEDs, as a rule, have a much longer service life compared with ordinary miniature incandescent bulbs, it has been shown that replacement of the luminous element including LEDs may sometimes become necessary.
In cases such as described above where LED luminous elements must be replaced, the entire printed circuit board must usually be removed from the automotive vehicle or other large system application so that the LED can be loosened from its soldered attachment and replaced. When the work effort involved in desoldering the LED is extreme, a typical solution has been to replace the entire printed circuit board including all of its components. Both methods, however, are costly.
In addition to the above-described needs for replacing LEDs, there also frequently exists the requirement for retrofitting or of simply supplementing the existing LEDs in order to retrofit or equip the target motor vehicle or larger system application with certain additional, improved, or other functions. Retrofitting existing printed circuit boards is oftentimes advantageous to reduce the multitude of required different printed circuit board types that must be produced and inventoried. The flexibility of existing printed circuit boards is enhanced when the desired functions can be selected during installation by mere insertion of the appropriate respective LEDs where needed.